[PATCH v2 2/2] dt-bindings: cpufreq: Document operating-points-v2-sunxi-cpu

[Yangtao Li <tiny.windzz@gmail.com>]

Allwinner Process Voltage Scaling Tables defines the voltage and
frequency value  based on the speedbin blown in the efuse combination.
The sunxi-cpufreq-nvmem driver reads the efuse value from the SoC to
provide the OPP framework with required information.
This is used to determine the voltage and frequency value for each
OPP of operating-points-v2 table when it is parsed by the OPP framework.

The "operating-points-v2-sunxi-cpu" DT extends the "operating-points-v2"
with following parameters:
- nvmem-cells (NVMEM area containig the speedbin information)
- opp-microvolt-<name>: voltage in micro Volts.
  At runtime, the platform can pick a <name> and matching
  opp-microvolt-<name> property

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
---
 .../bindings/opp/sunxi-nvmem-cpufreq.txt      | 166 ++++++++++++++++++
 1 file changed, 166 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/opp/sunxi-nvmem-cpufreq.txt

diff --git a/Documentation/devicetree/bindings/opp/sunxi-nvmem-cpufreq.txt b/Documentation/devicetree/bindings/opp/sunxi-nvmem-cpufreq.txt
new file mode 100644
index 000000000000..c81a2075b974
--- /dev/null
+++ b/Documentation/devicetree/bindings/opp/sunxi-nvmem-cpufreq.txt
@@ -0,0 +1,166 @@
+Allwinner Technologies, Inc. NVMEM CPUFreq and OPP bindings
+===================================
+
+For some SoCs, the CPU frequency subset and voltage value of each OPP
+varies based on the silicon variant in use. Allwinner Process Voltage
+Scaling Tables defines the voltage and frequency value  based on the
+speedbin blown in the efuse combination. The sunxi-cpufreq-nvmem driver
+reads the efuse value from the SoC to provide the OPP framework with
+required information.
+
+Required properties:
+--------------------
+In 'cpus' nodes:
+- operating-points-v2: Phandle to the operating-points-v2 table to use.
+
+In 'operating-points-v2' table:
+- compatible: Should be
+	- 'operating-points-v2-sunxi-cpu'.
+- nvmem-cells: A phandle pointing to a nvmem-cells node representing the
+		efuse registers that has information about the
+		speedbin that is used to select the right frequency/voltage
+		value pair.
+		Please refer the for nvmem-cells
+		bindings Documentation/devicetree/bindings/nvmem/nvmem.txt
+		and also examples below.
+
+In every OPP node:
+- opp-microvolt-<name>: Voltage in micro Volts.
+			At runtime, the platform can pick a <name> and
+			matching opp-microvolt-<name> property.
+			[See: opp.txt]
+
+Example 1:
+---------
+
+	cpus {
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		cpu0: cpu@0 {
+			compatible = "arm,cortex-a53";
+			device_type = "cpu";
+			reg = <0>;
+			enable-method = "psci";
+			clocks = <&ccu CLK_CPUX>;
+			clock-latency-ns = <244144>; /* 8 32k periods */
+			operating-points-v2 = <&cpu_opp_table>;
+			#cooling-cells = <2>;
+		};
+
+		cpu1: cpu@1 {
+			compatible = "arm,cortex-a53";
+			device_type = "cpu";
+			reg = <1>;
+			enable-method = "psci";
+			clocks = <&ccu CLK_CPUX>;
+			clock-latency-ns = <244144>; /* 8 32k periods */
+			operating-points-v2 = <&cpu_opp_table>;
+			#cooling-cells = <2>;
+		};
+
+		cpu2: cpu@2 {
+			compatible = "arm,cortex-a53";
+			device_type = "cpu";
+			reg = <2>;
+			enable-method = "psci";
+			clocks = <&ccu CLK_CPUX>;
+			clock-latency-ns = <244144>; /* 8 32k periods */
+			operating-points-v2 = <&cpu_opp_table>;
+			#cooling-cells = <2>;
+		};
+
+		cpu3: cpu@3 {
+			compatible = "arm,cortex-a53";
+			device_type = "cpu";
+			reg = <3>;
+			enable-method = "psci";
+			clocks = <&ccu CLK_CPUX>;
+			clock-latency-ns = <244144>; /* 8 32k periods */
+			operating-points-v2 = <&cpu_opp_table>;
+			#cooling-cells = <2>;
+		};
+        };
+
+        cpu_opp_table: opp_table {
+                compatible = "operating-points-v2-sunxi-cpu";
+                nvmem-cells = <&speedbin_efuse>;
+                opp-shared;
+
+                opp@480000000 {
+                        clock-latency-ns = <244144>; /* 8 32k periods */
+                        opp-hz = /bits/ 64 <480000000>;
+
+                        opp-microvolt-speed0 = <880000>;
+                        opp-microvolt-speed1 = <820000>;
+                        opp-microvolt-speed2 = <800000>;
+                };
+
+                opp@720000000 {
+                        clock-latency-ns = <244144>; /* 8 32k periods */
+                        opp-hz = /bits/ 64 <720000000>;
+
+                        opp-microvolt-speed0 = <880000>;
+                        opp-microvolt-speed1 = <820000>;
+                        opp-microvolt-speed2 = <800000>;
+                };
+
+                opp@816000000 {
+                        clock-latency-ns = <244144>; /* 8 32k periods */
+                        opp-hz = /bits/ 64 <816000000>;
+
+                        opp-microvolt-speed0 = <880000>;
+                        opp-microvolt-speed1 = <820000>;
+                        opp-microvolt-speed2 = <800000>;
+                };
+
+                opp@888000000 {
+                        clock-latency-ns = <244144>; /* 8 32k periods */
+                        opp-hz = /bits/ 64 <888000000>;
+
+                        opp-microvolt-speed0 = <940000>;
+                        opp-microvolt-speed1 = <820000>;
+                        opp-microvolt-speed2 = <800000>;
+                };
+
+                opp@1080000000 {
+                        clock-latency-ns = <244144>; /* 8 32k periods */
+                        opp-hz = /bits/ 64 <1080000000>;
+
+                        opp-microvolt-speed0 = <1060000>;
+                        opp-microvolt-speed1 = <880000>;
+                        opp-microvolt-speed2 = <840000>;
+                };
+
+                opp@1320000000 {
+                        clock-latency-ns = <244144>; /* 8 32k periods */
+                        opp-hz = /bits/ 64 <1320000000>;
+
+                        opp-microvolt-speed0 = <1160000>;
+                        opp-microvolt-speed1 = <940000>;
+                        opp-microvolt-speed2 = <900000>;
+                };
+
+                opp@1488000000 {
+                        clock-latency-ns = <244144>; /* 8 32k periods */
+                        opp-hz = /bits/ 64 <1488000000>;
+
+                        opp-microvolt-speed0 = <1160000>;
+                        opp-microvolt-speed1 = <1000000>;
+                        opp-microvolt-speed2 = <960000>;
+                };
+        };
+....
+soc {
+....
+	sid: sid@3006000 {
+		compatible = "allwinner,sun50i-h6-sid";
+		reg = <0x03006000 0x400>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+		....
+		speedbin_efuse: speed@1c {
+			reg = <0x1c 4>;
+		};
+        };
+};
-- 
2.17.0